With all those missing folder, wouldn't it just be easier to re-install DW? You can re-install a single app from the Suite without affecting the rest. Furthermore, even DW's local copy of the Site Definitions are in that configuration folder in the library which is obviously missing so there is really nothing left to lose at this point. See David's thread on the site definitions location ( http://forums.adobe.com/thread/439283 ).

Before you do re-install though I'd recommend running a repair permissions on your entire system to ensure the installer can write where it needs to. That can be found in the Disk Utility (cmd+space to get spotlight and then type disk utility to find it quick).